1. Field of the Invention
The present invention relates to a low resistance value resistor suitable for use in applications such as current detector and the like, and relates in particular to a resistor made of a resistive alloy and having an electrode placed at each end of the resistor body.
2. Description of the Related Art
Low resistance value resistors of a plate- or ribbon-shape having an electrode placed at each end of a metallic base material are widely used in applications such as current detector and the like because of their characteristics of good heat dissipation and high current carrying capacity. Metallic materials serving as a resistor body include, for example, copper-nickel alloys, nichrome alloys, iron-chromium alloys and manganese alloys, and an electrode is placed at each end of the resistor. Conventional electrode structures are generally based on electroplated electrode on a metallic material mentioned above.
However, it is difficult to form a thick deposit on the resistor body by electroplating, and for this reason, uniformity of electric potential through the electrode is low, and the current path can not be stabilized, thereby making it difficult to manufacture low resistance value resistors of high precision. Also, bonding between the metallic material constituting the resistor body and the electrode produced by electroplating is weak, and problems occur when it is necessary to bend the resistor body for use, because the bond is susceptible to mechanical, thermal and electrical stresses.
Also, in some low resistance value resistors, instead of electroplated electrodes, electrodes are sometimes made by affixing a strip of copper or nickel to the resistor body by means of electron beam welding and the like. Even in such cases, such spot-type joining techniques produce small areas of contact through the attached strip, and similar problems of insufficient bonding strength and non-uniformity of current distribution are created. Therefore, problems are encountered in attaining high precision in low resistance value resistors, and obtaining low values of the temperature coefficient of resistance (TCR).